Dignity is what people keep when they preserve their self-respect.
One with dignity demands respect and acts formally.
Acting with dignity can also mean navigating through a situation with eloquence and not losing one's cool.
One can lose their dignity temporarily but later gain it back.

If a girl consents to having a friends with benefits relationship with a guy, she may feel a loss of dignity after-wards if she would really rather have a boyfriend.
If you are drunk you lose your dignity.